1. Related Technical Fields
Related technical fields include data management systems and methods for updating data.
2. Related Art
Conventional navigation devices provide course guidance to a destination. Conventional navigation devices have a storage medium that stores map data related to maps and displaying maps, which is read out from the storage medium on a monitor together with a position of the vehicle detected by a GPS receiver. Conventional navigation devices generally have a built-in hard disk of a large storage capacity as a storage medium.
Such a built-in hard disk is configured to update the data stored in the aforementioned storage medium, not by replacing discs (e.g., DVD, CD-ROM and such), but by an updating file via, for example, a medium of a small capacity or a predefined communication network such as a mobile telephone.
Data is generally stored in the built-in hard disk in record units that include a plurality of fields. Such data is updated, not by updating the entirety of the stored data, but by updating data in the record units according to “differential updating” (see, e.g., Japanese Patent Application Publication No. JP-A-2004-287705).
In “differential updating,” an updating file having only new records which require updating is created and the navigation device updates the data stored in the storage medium by way of accepting the entry of the updating file and renewing each records-record subject to update stored in the storage medium by replacing all of the data of each records record which required updating. Even though such records may have only required updating of as little as single byte of data. Therefore, the amount of data in the aforementioned updating file is less than all of the data stored in the built-in hard disk because the records that do not require updating are not included.
Another navigation device is known, which gives search guidance of spot information, by storing data relating to spot information in a storage medium and displaying the information retrieved from the storage medium on a monitor (see, e.g., Japanese Patent Application Publication No. JP-A-2005-25672 and Japanese Industrial Standards (JIS) D-0810, for example). Specifically, with a navigation device, which provides search guidance of spot information, information data and data specifying the information data is stored in an information data frame data. The information data and specifying data is stored for each category specified by retrieval keys.
By the entry of retrieval keys (such as a name pronunciation, telephone number, and address of a spot), pertinent data in the category specified by the retrieval keys entered is extracted successively from the data frame and the name of the spot contained in the extracted pertinent data are displayed on a monitor. Further, when one of the pertinent displayed data is selected, an address is referenced, the information data specified by the pertinent data is extracted successively from the aforementioned information data frame, and the detailed information of the spot and such contained in the extracted information data is displayed on the monitor.
When updating the aforementioned pertinent data and the aforementioned information data, differential updating may be used. Specifically, as shown in FIGS. 7 and 8, an updating file that contains both the entire pertinent data frame in which the latest updating pertinent data to be stored in the storage medium are stored and the entire information data frame in which the latest updating information data to be stored in the storage medium are stored may be accepted (S11). Then, as indicated by the arrow A′ in FIG. 8, the navigation device extracts information data subject to update (S12) and, as indicated by the arrows a′ in FIG. 8, updates the extracted information data with the updating information data contained in the updating file (S13). Similarly, as indicated by the arrow B′ in FIG. 8, the navigation device extracts pertinent data subject to update (S14) and, as indicated by the arrow b′ in FIG. 8, updates the extracted pertinent data with the updating pertinent data contained in the aforementioned updating file (S15).